Technique for Establishing a Mesh Network

ABSTRACT

In order to establish a mesh network, an electronic device may iteratively identify one or more mesh-network nodes and may determine associated duty-cycle ratios based on communication with the one or more mesh-network nodes. In particular, the electronic device may select candidate mesh-network nodes based on estimated throughput metrics of their communication with a root device in the mesh network. Then, for each of the candidate mesh-network nodes, the electronic device may associate with a given candidate mesh-network node, and may measure the throughput of the given candidate mesh-network node during a time interval by communicating packets. Based on comparisons of the measured throughputs, the electronic device may identify the one or more mesh-network nodes in the candidate mesh-network nodes and may determine the associated duty-cycle ratios. Subsequently, the electronic device communicates information with the root device via the one or more mesh-network nodes based on the duty-cycle ratios.

BACKGROUND Field

The described embodiments relate to techniques for establishing awireless mesh network. In particular, the described embodiments relateto techniques for selecting intermediate nodes in a wireless meshnetwork.

Related Art

Many electronic devices are capable of wirelessly communicating withother electronic devices. For example, these electronic devices caninclude a networking subsystem that implements a network interface for:a cellular network (UMTS, LTE, etc.), a wireless local area network(e.g., a wireless network such as described in the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard or Bluetoothfrom the Bluetooth Special Interest Group of Kirkland, Wash.), and/oranother type of wireless network.

One approach to wireless communication is a wireless mesh network (whichis henceforth referred to as a ‘mesh network’). In a mesh network,multiple electronic devices (which are sometimes referred to as ‘nodes’)are organized in a mesh topology in which electronic devices communicatewith each other via zero or more intermediate electronic devices ornodes. Typically, an electronic device in a mesh network communicateswith its nearest neighbor(s). In a mesh network, the communicationbetween two electronic devices via an intermediate electronic device ornode is referred to as ‘one-hop’ communication, while the communicationbetween the two electronic devices via two intermediate electronicdevices or nodes is referred to as ‘two-hop’ communication. Similarly,the communication between the two electronic devices via N intermediateelectronic devices or nodes is referred to as ‘N-hop’ communication.

Mesh networks can have decentralized node associations, with no centralserver or management dictating the mesh-network topology. While thisarchitecture is relatively inexpensive, and is reliable and resilient,it can pose challenges. In particular, it can be difficult to organizeor assemble the electronic devices into a mesh network.

SUMMARY

The described embodiments relate to an electronic device thatestablishes a mesh network. This electronic device includes an interfacecircuit that communicates with two or more electronic devices toestablish the mesh network. During operation, the electronic deviceselects candidate mesh-network nodes based on estimated throughputmetrics of the two or more electronic devices to a root device in themesh network. Then, for each of the candidate mesh-network nodes, theelectronic device: associates with a given candidate mesh-network node;measures the throughput of the given candidate mesh-network node duringa time interval by communicating packets; and stores the measuredthroughput of the given candidate mesh-network node (e.g., in acomputer-readable memory). Moreover, the electronic device compares themeasured throughputs, identifies one or more mesh-network nodes in thecandidate mesh-network nodes and determines associated duty-cycle ratiosbased on the comparisons. Furthermore, the electronic devicecommunicates information with the root device via the one or moremesh-network nodes based on the duty-cycle ratios (e.g., packets arecommunicated to the root device via the one or more mesh-network nodes).Thus, the measured throughputs may be used to select the one or moremesh-network nodes that result in the best performance in the meshnetwork at a given time.

Note that an estimated throughput metric of the given candidatemesh-network node is based on one of: a received signal strengthindication (RSSI), airtime usage by the given candidate mesh-networknode, and an advertised throughput associated with the given candidatemesh-network node. Moreover, at least one of the airtime usage and theadvertised throughput may be included in beacons communicated in themesh network.

For example, the estimated throughput metric of the given candidatemesh-network node may correspond to a throughput between the givencandidate mesh-network node and the root device in the mesh network anda throughput metric between the given candidate mesh-network node andthe electronic device.

Furthermore, the measured throughput may include an uplink throughput.In some embodiments, the measured throughput corresponds to one hop inthe mesh network.

Additionally, the associating, measuring and storing may be performed ina round-robin fashion for the candidate mesh-network nodes.

When a measured throughput of a candidate mesh-network node exceeds theother measured throughputs by a predefined value, the one or moremesh-network nodes may include the candidate mesh-network node and theassociated duty-cycle ratio may be one hundred percent (i.e., subsequentcommunication may occur via this candidate mesh-network node).Alternatively, when maximum measured throughputs, which are associatedwith at least two candidate mesh-network nodes, are within thepredefined value of each other, the one or more mesh-network nodes mayinclude at least the two candidate mesh-network nodes and the associatedduty-cycle ratios may be based on ratios of the measured throughputs ofat least the two candidate mesh-network nodes (i.e., subsequentcommunication may occur via these candidate mesh-network nodes).

Note that the associating, measuring, storing, comparing, identifying,determining and communicating may be repeated until a convergencecriterion is achieved.

Moreover, the one or more mesh-network nodes may be identified and theduty-cycle ratios may be determined using Bayesian analysis.

Furthermore, the electronic device and the two or more electronicdevices may include access points.

In some embodiments, the electronic device includes: a processor; and amemory, coupled to the processor, which stores a program module that isexecuted by the processor. This program module may include instructionsfor at least some of the operations performed by the electronic device(i.e., at least some of the operations performed by the electronicdevice may be performed using software).

Moreover, the electronic device may include an antenna coupled to theinterface circuit.

Another embodiment provides a computer-program product for use with theelectronic device. This computer-program product includes instructionsfor at least some of the operations performed by the electronic device.

Another embodiment provides a method for establishing a mesh network.This method includes at least some of the operations performed by theelectronic device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram illustrating electronic devices wirelesslycommunicating in accordance with an embodiment of the presentdisclosure.

FIG. 2 is a flow diagram illustrating a method for establishing a meshnetwork during communication among the electronic devices in FIG. 1 inaccordance with an embodiment of the present disclosure.

FIG. 3 is a drawing illustrating iterative identification ofmesh-network nodes and determination of associated duty-cycle ratiosduring communication among the electronic devices in FIG. 1 inaccordance with an embodiment of the present disclosure.

FIG. 4 is a drawing illustrating communication among the electronicdevices in FIG. 1 in accordance with an embodiment of the presentdisclosure.

FIG. 5 is a block diagram illustrating one of the electronic devices ofFIG. 1 in accordance with an embodiment of the present disclosure.

Note that like reference numerals refer to corresponding partsthroughout the drawings. Moreover, multiple instances of the same partare designated by a common prefix separated from an instance number by adash.

DETAILED DESCRIPTION

In order to establish a mesh network association with a mesh-networknode, an electronic device may iteratively identify one or moremesh-network nodes and may determine associated duty-cycle ratios basedon communication with the one or more mesh-network nodes. In particular,the electronic device may select candidate mesh-network nodes based onestimated throughput metrics of their communication with a root devicein the mesh network. Then, for each of the candidate mesh-network nodes,the electronic device may associate with a given candidate mesh-networknode, and may measure the throughput of the given candidate mesh-networknode during a time interval by communicating packets. Based oncomparisons of the measured throughputs, the electronic device mayidentify the one or more mesh-network nodes in the candidatemesh-network nodes and may determine the associated duty-cycle ratios.Subsequently, the electronic device communicates information with theroot device via the one or more mesh-network nodes based on theduty-cycle ratios (e.g., packets are communicated to the root device viathe one or more mesh-network nodes). This may allow that analysis to berefined so that one of the mesh-network nodes can be selected for use insubsequent communication of packets between the electronic device andthe root device in the mesh network.

In some embodiments, the electronic device repeats the aforementionedoperations one or more times (e.g., iteratively or periodically). Thismay allow the electronic device to facilitate establishment of the meshnetwork, as well as maintaining an optimal configuration or architecturein the mesh network. In particular, the electronic device may use themeasured throughputs to select the one or more mesh-network nodes thatresult in the best performance in the mesh network at a given time. Forexample, the electronic device may: maximize the throughput between theelectronic device and the root device), recover from failure, and/oradapt to a changing radio-frequency environment.

In the discussion that follows the electronic devices include radiosthat communicate packets in accordance with a communication protocol,such as an Institute of Electrical and Electronics Engineers (IEEE)802.11 standard (which is sometimes referred to as ‘Wi-Fi®,’ from theWi-Fi Alliance of Austin, Tex.), Bluetooth (from the Bluetooth SpecialInterest Group of Kirkland, Wash.), and/or another type of wirelessinterface (such as another wireless-local-area-network interface). Inthe discussion that follows, Wi-Fi is used as an illustrative example.However, a wide variety of communication protocols may be used.

Communication among electronic devices is shown in FIG. 1, whichpresents a block diagram illustrating electronic devices 110 (such asaccess points) wirelessly communicating in a mesh network 112 accordingto some embodiments. In particular, these electronic devices maywirelessly communicate while: transmitting advertising frames onwireless channels, detecting one another by scanning wireless channels,establishing connections (for example, by transmitting associationrequests), and/or transmitting and receiving packets (which may includethe association requests and/or additional information as payloads).

As described further below with reference to FIG. 5, electronic devices110 may include subsystems, such as a networking subsystem, a memorysubsystem and a processor subsystem. In addition, electronic devices 110may include radios 114 in the networking subsystems. More generally,electronic devices 110 can include (or can be included within) anyelectronic devices with the networking subsystems that enable electronicdevices 110 to wirelessly communicate with each other. This wirelesscommunication can comprise transmitting advertisements on wirelesschannels to enable electronic devices to make initial contact or detecteach other, followed by exchanging subsequent data/management frames(such as association requests and responses) to establish a connection,configure security options (e.g., Internet Protocol Security), transmitand receive packets or frames via the connection, etc.

As can be seen in FIG. 1, wireless signals 116 (represented by jaggedlines) are transmitted by radios 114 in electronic devices 110. Forexample, radio 114-1 in electronic device 110-1 may transmit information(such as packets) using wireless signals. These wireless signals arereceived by radios 114 in one or more other electronic devices (such aselectronic devices 110-2 and 110-3). This may allow electronic device110-1 to communicate information to electronic devices 110-2 and/or110-3. Furthermore, electronic devices 110-2 and/or 110-3 may wirelesslytransmit packets to electronic device 110-4, which is a root device inmesh network 112. This root device may couple mesh network 112 to awired network 118, such as the Internet and/or an intranet. Note thatelectronic device 110-1 may access network 118 via at least one ofelectronic devices 110-2 and 110-3, and electronic device 110-4. Thus,electronic device 110-1 may access network 118 via one hop (such as viaelectronic device 110-2 or electronic device 110-3, which thencommunicates with electronic device 110-4) or two hops (such as viaelectronic device 110-2, which communicates with electronic device110-3, which in turn communicates with electronic device 110-4) in meshnetwork 112.

Note that the communication among electronic devices 110 (such asbetween at least any two of electronic devices 110) may be characterizedby a variety of performance metrics, such as: a data rate, a data ratefor successful communication (which is sometimes referred to as a‘throughput’), an error rate (such as a retry or resend rate), amean-square error of equalized signals relative to an equalizationtarget, intersymbol interference, multipath interference, asignal-to-noise ratio, a width of an eye pattern, a ratio of number ofbytes successfully communicated during a time interval (such as 1-10 s)to an estimated maximum number of bytes that can be communicated in thetime interval (the latter of which is sometimes referred to as the‘capacity’ of a communication channel or link), and/or a ratio of anactual data rate to an estimated data rate (which is sometimes referredto as ‘utilization’). In some embodiments, the communication amongelectronic devices 110 (such as between at least any two of electronicdevices 110) is characterized by an error-rate model, which compares theerror rate during communication at the data rate.

However, it can be difficult to organize electronic devices 110 intomesh network 112. For example, it can be difficult to select theappropriate intermediate node(s) in mesh network 112 between electronicdevice 110-1 and electronic device 110-4 (which are henceforth referredto as mesh-network nodes) to optimize at least one performance metric(such as the throughput between electronic device 110-1 and electronicdevice 110-4) in the presence of either static or dynamic radiofrequency environments. In addition, the performance during thecommunication may change or degrade (e.g., there may be too manyelectronic devices communicating with one of the mesh-network nodes, theamount of information that electronic device 110-1 needs to communicatewith the mesh-network node(s) may exceed the capacity, there may beinterference or movement, and/or there may be another factor that mayaffect the performance, etc.). Therefore, the appropriate mesh-networknode(s) may need to be changed based on current conditions in meshnetwork 112, but once again it can be difficult to select theappropriate mesh-network node(s) to maintain or optimize theperformance. If the mesh-network node(s) is selected incorrectly, theremay be a significant opportunity cost in degraded or sub-optimalperformance in mesh network 112, which, in turn, may increase the numberof packets that are resent and, thus, may increase the latency of thecommunication and may degrade the experience of a user of electronicdevice 110-1.

In order to address this problem, electronic device 110-1 may implementa communication technique (which is described further below withreference to FIGS. 2-4). In particular, electronic device 110-1 mayselect candidate mesh-network nodes (such as electronic devices 110-2and 110-3) based on estimated throughput metrics of electronic devices110-2 and 110-3 to a root device (i.e., electronic device 110-4) in meshnetwork 112. Note that an estimated throughput metric of the givencandidate mesh-network node (such as electronic device 110-2) may bebased on: a received signal strength indication (RSSI); and airtimeusage by the given candidate mesh-network node, and/or an advertisedthroughput associated with the given candidate mesh-network node.Moreover, at least one of the airtime usage and the advertisedthroughput may be included in beacons communicated in mesh network 112.For example, the RSSI may be mapped (using a predefined table of RSSIand throughput values) to an estimated throughput metric, so that 70 dBis mapped to 400 Mb/s. In some embodiments, such as when the airtimeusage is less than 60%, the advertised throughputs in beacons are usedto calculate the estimated throughput metric. In particular, theestimated throughput metric of the given candidate mesh-network node maycorrespond to a throughput between the given candidate mesh-network nodeand the root device (T_(RD)) in mesh network 112 and a throughput metricbetween the given candidate mesh-network node and electronic device110-1 (T_(IN)). For example, the estimated throughput metric may be

$\frac{1}{\left( T_{RD} \right)^{- 1} + \left( T_{IN} \right)^{- 1}}.$

Then, for each of the candidate mesh-network nodes, electronic device110-1: associates with a given candidate mesh-network node (such aselectronic device 110-2);

measures the throughput (and, more generally, a throughput metric) ofthe given candidate mesh-network node during a time interval (such as 10s, 1 minute or 3 minutes) by communicating packets; and stores themeasured throughput of the given candidate mesh-network node (e.g., in acomputer-readable memory). For example, a measured throughput may be anuplink throughput via electronic devices 110-2 or 110-3 to electronicdevice 110-4 (such as an uplink throughput associated with at least onehop in mesh network 112). Note that the associating, measuring andstoring may be performed in a round-robin fashion for the candidatemesh-network nodes (e.g., first for electronic device 110-2 and then forelectronic device 110-3).

Moreover, electronic device 110-1 compares the measured throughputs,identifies one or more mesh-network nodes in the candidate mesh-networknodes and determines associated duty-cycle ratios based on thecomparisons. For example, as described further below with reference toFIG. 3, when a measured throughput of a candidate mesh-network nodeexceeds the other measured throughputs by a predefined value (such as 5,10 or 20%), the one or more mesh-network nodes may include the candidatemesh-network node and the associated duty-cycle ratio may be one hundredpercent (i.e., subsequent communication may occur via this candidatemesh-network node, such as electronic device 110-2 or 110-3).Alternatively, when maximum measured throughputs, which are associatedwith at least two candidate mesh-network nodes (such as electronicdevices 110-2 and 110-3), are within the predefined value of each other,the one or more mesh-network nodes may include at least the twocandidate mesh-network nodes and the associated duty-cycle ratios may bebased on ratios of the measured throughputs of at least the twocandidate mesh-network nodes (i.e., subsequent communication may occurvia these candidate mesh-network nodes).

Furthermore, electronic device 110-1 may communicate information (suchas packets) with the root device via the one or more mesh-network nodesbased on the duty-cycle ratios. (As noted previously, this may allowthat analysis to be refined so that one of the mesh-network nodes can beselected for use in subsequent communication of packets between theelectronic device and the root device in the mesh network.) For example,if electronic devices 110-2 and 110-3 are identified as mesh-networknodes, electronic device 110-1 may communicate the information bytime-domain multiplexed communication of the information with electronicdevices 110-2 and 110-3. Thus, if a duty-cycle ratio of electronicdevice 110-2 is 40% and a duty-cycle ratio of electronic device 110-3 is60%, electronic device 110-1 may communicate packets with electronicdevice 110-2 40% of the time and may communicate packets with electronicdevice 110-3 60% of the time. Thus, the communication times withelectronic devices 110-2 and 110-3, respectively, may be determined byscaling a time interval by the duty-cycle ratios of electronic devices110-2 and 110-3.

Note that the associating, measuring, storing, comparing, identifying,determining and communicating may be repeated by electronic device 110-1until a convergence criterion is achieved. For example, electronicdevice 110-1 may repeat these operations after a time interval (such as3 minutes) until the determined duty-cycle ratios in three consecutiveiterations are within 5, 10 or 20% of each other. Thus, the mesh-networknodes may be determined iteratively and dynamically (as opposed toselecting mesh-network nodes based on a static performance metric orbased on a static criterion). In addition, the communication techniquemay be repeated as needed (such as when the throughput in mesh network112 degrades by more than 10 or 20% for 10 s, 1 minute or 3 minutes)and/or regularly or periodically (such as every hour or once a day).

Moreover, a variety of analysis techniques may be used to identify themesh-network nodes and to determine the duty-cycle ratios. For example,the one or more mesh-network nodes may be identified and the duty-cycleratios may be determined using Bayesian analysis. Alternatively oradditionally, an optimization technique may be used, such as: thesimplex technique, Newton's method, a quasi-Newton method, steepestdescents, a genetic technique, simulated annealing, etc.

While the preceding discussion illustrated establishing (andmaintaining) mesh network 112 based on estimated throughput metrics andmeasured throughputs, in other embodiments one or more additional ordifferent performance metrics may be used. For example, electronicdevice 110-1 may track data rates during communication in mesh network112 (which may be specified by interface circuits in electronic device110-1 and electronic devices 110-2 and 110-3) and may receive feedbackabout the communication from electronic devices 110-2 and 110-3 (such aswhether packets were successfully received based on acknowledgmentmessages). Moreover, electronic device 110-1 may determine an observeddistribution of the data rates (such as data rate as a function ofpercentage or percentile of the communication, e.g., 5% of thecommunicated packets, etc.), which is an illustration of a throughputmetric. In particular, the observed distribution may be sorted (such aspercentile ranks of the observed distribution), e.g., into a histogram.However, the observed distribution may be other than a histogram. Notethat, in general, an ‘observed distribution’ may include a collection ofobserved value samples from a random process (e.g., the measuredthroughput) that may be sorted from best to worst (or vice versa).Furthermore, the observed value samples may be decimated (e.g., everyother value or, more generally, 1/N values may be removed from thesorted list, where N is an integer) to bound the size of the observeddistribution without sacrificing statistical information.

Alternatively or additionally, the throughput metric determined byelectronic device 110-1 may be the ratio of the measured data rateduring the communication to an estimated data rate during thecommunication. Thus, the throughput metric may be the utilization, e.g.,the ratio of the data rate during successful communication of packets(as indicated by acknowledgment messages) to the estimated data rate ofthe communication channel or link. Note that the estimated data rate maybe the estimated maximum data rate or throughput as determined using anerror-rate model for the communication.

Then, electronic device 110-1 may compare the throughput metric to athreshold value. For example, when the throughput metric is based on theobserved distribution, the threshold value may be a target data rateassociated with a percentile on the observed distribution, such as adata rate or throughput of 10 kbps for the 50^(th) percentile in theobserved distribution. Alternatively or additionally, when thethroughput metric is the utilization, the threshold value may be atarget utilization, such as 90%. Electronic devices having throughputmetrics exceeding the threshold value may be selected by electronicdevice 110-1 as candidate mesh-network nodes.

In the described embodiments, processing a packet or frame in electronicdevices 110 includes: receiving the wireless signals with the packet orframe; decoding/extracting the packet or frame from the receivedwireless signals to acquire the packet or frame; and processing thepacket or frame to determine information contained in the packet orframe (such as the feedback about the performance during thecommunication).

Although we describe the network environment shown in FIG. 1 as anexample, in alternative embodiments, different numbers or types ofelectronic devices may be present. For example, some embodimentscomprise more or fewer electronic devices. As another example, inanother embodiment, different electronic devices are transmitting and/orreceiving packets or frames.

FIG. 2 presents embodiments of a flow diagram illustrating method 200for establishing a mesh network that may be performed by an electronicdevice, such as one of electronic devices 110 in FIG. 1 (e.g.,electronic device 110-1), according to some embodiments. Duringoperation, the electronic device selects candidate mesh-network nodes(operation 210) based on estimated throughput metrics of two or moreelectronic devices to a root device in the mesh network. (Alternatively,in some embodiments the estimated throughput metrics of the two or moreelectronic devices are to a network, such as the Internet.)

Then, the electronic device performs one or more operations for each ofthe candidate mesh-network nodes. In particular, the electronic device:associates with a given candidate mesh-network node (operation 212);measures a throughput (operation 214) of the given candidatemesh-network node during a time interval by communicating packets (e.g.,by transmitting and receiving the packets); and stores the measuredthroughput (operation 216) of the given candidate mesh-network node.These operations are repeated (operation 218) at least once for each ofthe candidate mesh-network nodes. (In subsequent, optional iterations,the operations may be repeated for a selected subset of one or moremesh-network nodes to further refine the analysis. This may allow one ofthe mesh-network nodes to be ultimately and accurately selected for usein communicating packets between the electronic device and the rootdevice at a given time.)

Next, the electronic device compares the measured throughputs (operation220). Moreover, the electronic device identifies one or moremesh-network nodes (operation 222) in the candidate mesh-network nodesand determines associated duty-cycle ratios (operation 222) based on thecomparisons. Furthermore, the electronic device communicates informationwith the root device (operation 224) via the one or more mesh-networknodes based on the duty-cycle ratios. For example, the electronic devicemay communicate packets to the root device via the one or moremesh-network nodes.

In this way, the electronic device (for example, an interface circuit, adriver and/or software executed in an environment of the transmittingelectronic device) may facilitate communication with one or more otherelectronic devices in the mesh network. In particular, the electronicdevice may identify the one or more mesh-network nodes that increase oroptimize the throughput between the electronic device and the rootdevice in the mesh network. This may reduce latency and, thus, mayimprove the user experience when communicating via the electronic deviceand the mesh network.

In some embodiments of method 200 (FIG. 2), there may be additional orfewer operations. For example, operations 212-222 in method 200 may berepeated two or more times, so that the one or more mesh-network nodesare identified and the associated duty-cycle ratios are determinediteratively until a convergence criterion is achieved. Moreover, theorder of the operations may be changed, and/or two or more operationsmay be combined into a single operation.

As noted previously, in some embodiments the mesh-network nodes areidentified by measuring throughput during wireless communication ofpackets in the mesh network. For example, the one or more mesh-networknodes may be identified and the associated duty-cycle ratios may bedetermined based on measured throughputs, which may allow subsequentiterations of the communication technique to be used to converge on oneof the mesh-network nodes to use as an uplink neighbor in the meshnetwork at a given time. This is shown in FIG. 3, which presents adrawing illustrating the identification of one or more mesh-networknode(s) 314 and the determination of associated duty-cycle ratio(s) 316during communication among electronic devices (such as electronic device110-1 and electronic devices 110-2 and 110-3 in FIG. 1) according tosome embodiments. In particular, electronic device 110-1 may track ormeasure throughputs 312 during time intervals 310 (such as 3 minutes)during the communication. Then, electronic device 110-1 may identify oneor more mesh-network node(s) 314 and may determine associated duty-cycleratio(s) 316. For example, when the measured throughput of electronicdevice 110-2 is more than 10 or 20% greater than the measured throughputof electronic device 110-3 during time interval A, mesh-network node(s)314 include electronic device 110-2 and duty-cycle(s) 316 is 100%.Alternatively, when the measured throughput of electronic device 110-2is within 10 or 20% of the measured throughput of electronic device110-3 during time interval B, mesh-network node(s) 314—includeselectronic devices 110-2 and 110-3 and the associated duty-cycleratios(s) 316 are 60% and 40%. Note that the duty-cycle ratios may bedetermined based on the ratio of the measured throughputs. Inparticular, the ratio of the measured throughputs in time interval B is0.8, so the duty-cycle ratios are, respectively, 10% above and below50%.

Embodiments of the communication technique are further illustrated inFIG. 4, which presents a drawing illustrating communication amongelectronic device 110-1 and electronic devices 110-2 and 110-3 (FIG. 1)according to some embodiments. In particular, during the communicationtechnique electronic device 110-1 may receive beacons 410 fromelectronic devices 110-2 and 110-3. These beacons may include estimatedthroughput metrics for electronic devices 110-2 and 110-3, which werepreviously determined by electronic devices 110-2 and 110-3. Based onthe estimated throughput metrics, electronic device 110-1 may selectelectronic devices 110-2 and 110-3 as candidate mesh-network nodes 412.

Then, electronic device 110-1 may: associate 414 with electronic device110-2; and measure the throughput of electronic device 110-2 based oncommunication 416 of packets between electronic devices 110-1 and 110-2.Moreover, electronic device 110-1 may: associate 418 with electronicdevice 110-3; and measure the throughput of electronic device 110-3based on communication 420 of packets between electronic devices 110-1and 110-3.

Next, electronic device 110-1 may compare 422 the measured throughputs.Furthermore, electronic device 110-1 may identify 424 one or moremesh-network nodes and may determine 424 the associated duty-cycleratios. As noted previously, the one or more mesh-network nodes and theassociated duty-cycle ratios may be used in subsequent iterations of thecommunication technique (and, in particular, measurements ofthroughputs) to converge on one of the mesh-network nodes to use whencommunicating packets to the root device in the mesh network at a giventime (i.e., to determine the best uplink neighbor of electronic device110-1 in the mesh network at the given time).

In an exemplary embodiment, measured throughput is used in thecommunication technique to select an uplink neighbor (i.e., amesh-network node). In particular, data throughput may change over time.Consequently, when to revisit a neighbor to measure the throughput canbe a challenging issue. In order to address this issue, asimulated-annealing technique may be used to search for an approximationto a global optimum in a probabilistic manner. It this approach, themesh-network node or uplink neighbor may be changed when, based onhistorical data, a different uplink neighbor is likely offer higherthroughput than the current uplink neighbor. The probability of makingthe uplink switch may be specified by an acceptance probability functionthat depends on the throughput of candidate uplinks and on a globaltime-varying parameter, which is temperature. The simulated-annealingtechnique may initially starts with high temperature, and then decreasesit subsequent iterations following an ‘annealing schedule’ or mean timebetween change (MTBC).

In this way, the mesh network is expected to change the uplink neighborswith small throughput changes, which become less sensitive as timesprogresses. At a high simulated-annealing temperature, the mesh networkmay be very sensitive to changes in the throughput of the current uplinkneighbor or mesh-network node. Alternatively, at low simulated-annealingtemperature, the mesh network may be less sensitive. Note that the MTBCmay control the temperature in the simulated-annealing technique to meetthe desired interval between uplink changes. Initially (in first fewhours), there may be more frequent uplink changes as the throughputs ofthe different uplinks are measured, and then may slowly drift toward theMTBC.

For each candidate mesh-network node or candidate uplink neighbor, theelectronic device (such as an access point) may maintain severalcumulative distribution functions to store uplink throughputmeasurements and uplink/downlink RSSI. Initially, the throughput may becalculated by mapping an RSSI to a throughput using a predefinedconversion table. The throughput of the best candidate mesh-network nodebased on this mapping may be stored in a cumulative distributionfunction. Then, this candidate mesh-network node may be compared toanother candidate mesh-network node (or candidate uplink neighbor). Thiscomparison may involve the communication technique described previouslywith reference FIG. 2. The result of this comparison is that one of thecandidate mesh-network work nodes is selected as the mesh-network nodefor use in subsequent communication of packets with the root device inthe mesh network. Note that when the mesh-network node or uplinkneighbor is switched, it may remain the mesh-network node for at least aminimum uplink hold time (such as 3 minutes, 10 minutes, 1 hour, 3hours, etc.) in order to get accurate throughput measurements for use inthe analysis.

Furthermore, for the current mesh-network node of uplink neighbor, theelectronic device may store the uplink throughput and theuplink/downlink RSSI values in a correspondingcumulative-distribution-function data structure. Moreover, the uplinkthroughput may be compared to that of a neighboring electronic device inthe mesh network (i.e., a candidate mesh-network node) after the uplinkhold time has expired.

For the candidate mesh-network nodes that are explored, the measuredthroughputs may be maintained or stored in an uplink throughput history.Then, every five seconds, the median estimated throughput metric to theroot device or the core network via the current uplink neighbor iscompared to the median estimated throughput metric of the otherneighboring electronic devices. The communication technique may use thisinformation to determine whether to switch to a new uplink neighbor orto stay with the current uplink neighbor depending on the potentialimprovement/degradation. If the estimated throughput metric of thecurrent uplink neighbor is much lower than that of a neighboringelectronic device, the electronic device may change the mesh-networknode to this neighboring electronic device with a high probability.Alternatively, if the estimated throughput metric of the current uplinkneighbor is much higher than the neighboring electronic device, theelectronic device may switch the mesh-network node to this neighboringelectronic device with a low probability. Note that downlink estimatedthroughput metric from the parents in the mesh network may not be usedin the communication technique in order to reduce the overallcomplexity.

The end result of the communication technique is that the bestneighboring electronic device may be used most frequently and for themajority of time. The other neighboring electronic devices may be testedfrom time to time. Moreover, the frequency of tests and the averageduration of the stay may depend on how much worse the alternativecandidate mesh-network nodes are compared to the current uplinkneighbor. The worst uplink neighbors may be tested very rarely and onlyfor shorter periods of time.

We now describe embodiments of the electronic device. FIG. 5 presents ablock diagram illustrating an electronic device 500, such as one ofelectronic devices 110 in FIG. 1 (e.g., electronic device 110-1). Thiselectronic device includes processing subsystem 510, memory subsystem512, and networking subsystem 514. Processing subsystem 510 includes oneor more devices configured to perform computational operations. Forexample, processing subsystem 510 can include one or moremicroprocessors, application-specific integrated circuits (ASICs),microcontrollers, programmable-logic devices, and/or one or more digitalsignal processors (DSPs).

Memory subsystem 512 includes one or more devices for storing dataand/or instructions for processing subsystem 510 and networkingsubsystem 514. For example, memory subsystem 512 can include dynamicrandom access memory (DRAM), static random access memory (SRAM), and/orother types of memory. In some embodiments, instructions for processingsubsystem 510 in memory subsystem 512 include: one or more programmodules or sets of instructions (such as program module 522 or operatingsystem 524), which may be executed by processing subsystem 510. Notethat the one or more computer programs may constitute a computer-programmechanism. Moreover, instructions in the various modules in memorysubsystem 512 may be implemented in: a high-level procedural language,an object-oriented programming language, and/or in an assembly ormachine language. Furthermore, the programming language may be compiledor interpreted, e.g., configurable or configured (which may be usedinterchangeably in this discussion), to be executed by processingsubsystem 510.

In addition, memory subsystem 512 can include mechanisms for controllingaccess to the memory. In some embodiments, memory subsystem 512 includesa memory hierarchy that comprises one or more caches coupled to a memoryin electronic device 500. In some of these embodiments, one or more ofthe caches is located in processing subsystem 510.

In some embodiments, memory subsystem 512 is coupled to one or morehigh-capacity mass-storage devices (not shown). For example, memorysubsystem 512 can be coupled to a magnetic or optical drive, asolid-state drive, or another type of mass-storage device. In theseembodiments, memory subsystem 512 can be used by electronic device 500as fast-access storage for often-used data, while the mass-storagedevice is used to store less frequently used data.

Networking subsystem 514 includes one or more devices configured tocouple to and communicate on a wired and/or wireless network (i.e., toperform network operations), including: control logic 516, an interfacecircuit 518 and one or more antennas 520. (While FIG. 5 includes one ormore antennas 520, in some embodiments electronic device 500 includesone or more nodes, such as one or more nodes 508, e.g., a pad, which canbe coupled to one or more antennas 520. Thus, electronic device 500 mayor may not include one or more antennas 520. Note that the one or morenodes may include an input node or an output node.) For example,networking subsystem 514 can include a Bluetooth networking system, acellular networking system (e.g., a 3G/4G network such as UMTS, LTE,etc.), a universal serial bus (USB) networking system, a networkingsystem based on the standards described in IEEE 802.11 (e.g., a Wi-Finetworking system), an Ethernet networking system, and/or anothernetworking system.

Networking subsystem 514 includes processors, controllers,radios/antennas, sockets/plugs, and/or other devices used for couplingto, communicating on, and handling data and events for each supportednetworking system. Note that mechanisms used for coupling to,communicating on, and handling data and events on the network for eachnetwork system are sometimes collectively referred to as a ‘networkinterface’ for the network system. Moreover, in some embodiments a‘network’ between the electronic devices does not yet exist. Therefore,electronic device 500 may use the mechanisms in networking subsystem 514for performing simple wireless communication between the electronicdevices, e.g., transmitting advertising or beacon frames and/or scanningfor advertising frames transmitted by other electronic devices asdescribed previously.

Within electronic device 500, processing subsystem 510, memory subsystem512, and networking subsystem 514 are coupled together using bus 528.Bus 528 may include an electrical, optical, and/or electro-opticalconnection that the subsystems can use to communicate commands and dataamong one another. Although only one bus 528 is shown for clarity,different embodiments can include a different number or configuration ofelectrical, optical, and/or electro-optical connections among thesubsystems.

In some embodiments, electronic device 500 includes a display subsystem526 for displaying information on a display, which may include a displaydriver and the display, such as a liquid-crystal display, a multi-touchtouchscreen, etc.

Electronic device 500 can be (or can be included in) any electronicdevice with at least one network interface. For example, electronicdevice 500 can be (or can be included in): a desktop computer, a laptopcomputer, a subnotebook/netbook, a server, a tablet computer, asmartphone, a cellular telephone, a consumer-electronic device, aportable computing device, an access point, a router, a switch,communication equipment, test equipment, and/or another electronicdevice.

Although specific components are used to describe electronic device 500,in alternative embodiments, different components and/or subsystems maybe present in electronic device 500. For example, electronic device 500may include one or more additional processing subsystems 510, memorysubsystems 512, networking subsystems 514, and/or display subsystems526. Additionally, one or more of the subsystems may not be present inelectronic device 500. Moreover, in some embodiments, electronic device500 may include one or more additional subsystems that are not shown inFIG. 5. Also, although separate subsystems are shown in FIG. 5, in someembodiments, some or all of a given subsystem or component can beintegrated into one or more of the other subsystems or component(s) inelectronic device 500. For example, in some embodiments program module522 is included in operating system 524.

Moreover, the circuits and components in electronic device 500 may beimplemented using any combination of analog and/or digital circuitry,including: bipolar, PMOS and/or NMOS gates or transistors. Furthermore,signals in these embodiments may include digital signals that haveapproximately discrete values and/or analog signals that have continuousvalues. Additionally, components and circuits may be single-ended ordifferential, and power supplies may be unipolar or bipolar.

An integrated circuit may implement some or all of the functionality ofnetworking subsystem 514, such as a radio. Moreover, the integratedcircuit may include hardware and/or software mechanisms that are usedfor transmitting wireless signals from electronic device 500 andreceiving signals at electronic device 500 from other electronicdevices. Aside from the mechanisms herein described, radios aregenerally known in the art and hence are not described in detail. Ingeneral, networking subsystem 514 and/or the integrated circuit caninclude any number of radios. Note that the radios in multiple-radioembodiments function in a similar way to the described single-radioembodiments.

In some embodiments, networking subsystem 514 and/or the integratedcircuit include a configuration mechanism (such as one or more hardwareand/or software mechanisms) that configures the radio(s) to transmitand/or receive on a given communication channel (e.g., a given carrierfrequency). For example, in some embodiments, the configurationmechanism can be used to switch the radio from monitoring and/ortransmitting on a given communication channel to monitoring and/ortransmitting on a different communication channel. (Note that‘monitoring’ as used herein comprises receiving signals from otherelectronic devices and possibly performing one or more processingoperations on the received signals, e.g., determining if the receivedsignal comprises an advertising frame, calculating the estimatedthroughput metric, etc.)

While a communication protocol compatible with Wi-Fi was used as anillustrative example, the described embodiments of the communicationtechnique may be used in a variety of network interfaces. Furthermore,while some of the operations in the preceding embodiments wereimplemented in hardware or software, in general the operations in thepreceding embodiments can be implemented in a wide variety ofconfigurations and architectures. Therefore, some or all of theoperations in the preceding embodiments may be performed in hardware, insoftware or both. For example, at least some of the operations in thecommunication technique may be implemented using program module 522,operating system 524 (such as a driver for interface circuit 518) and/orin firmware in interface circuit 518. Alternatively or additionally, atleast some of the operations in the communication technique may beimplemented in a physical layer, such as hardware in interface circuit518.

Moreover, while the preceding embodiments illustrated the use of thecommunication technique and method 200 (FIG. 2) in electronic device110-1 (FIG. 1), in other embodiments the remedial action is performed:system-wide, per radio, per wireless network, per client, etc. Thus, atleast some of the operations in the communication technique and method200 (FIG. 2) may be performed by a remote electronic device or server.For example, the communication technique may be performed or coordinatedsystem-wide (such as for multiple electronic devices) by a centralserver.

In the preceding description, we refer to ‘some embodiments.’ Note that‘some embodiments’ describes a subset of all of the possibleembodiments, but does not always specify the same subset of embodiments.Moreover, note that the numerical values provided are intended asillustrations of the communication technique. In other embodiments, thenumerical values can be modified or changed.

The foregoing description is intended to enable any person skilled inthe art to make and use the disclosure, and is provided in the contextof a particular application and its requirements. Moreover, theforegoing descriptions of embodiments of the present disclosure havebeen presented for purposes of illustration and description only. Theyare not intended to be exhaustive or to limit the present disclosure tothe forms disclosed. Accordingly, many modifications and variations willbe apparent to practitioners skilled in the art, and the generalprinciples defined herein may be applied to other embodiments andapplications without departing from the spirit and scope of the presentdisclosure. Additionally, the discussion of the preceding embodiments isnot intended to limit the present disclosure. Thus, the presentdisclosure is not intended to be limited to the embodiments shown, butis to be accorded the widest scope consistent with the principles andfeatures disclosed herein.

What is claimed is:
 1. An electronic device, comprising: an interfacecircuit configured to communicate with second electronic devices,wherein the electronic device is configured to: select candidatemesh-network nodes to a root device in a mesh network; measurecommunication performance metrics of the candidate mesh-network nodes byproviding, to one or more output nodes of the electronic device, packetsaddressed to the candidate mesh-network nodes, and receiving, from oneor more input nodes of the electronic device, acknowledgments associatedwith the candidate mesh-network nodes; identify one or more mesh-networknodes in the candidate mesh-network nodes and determine associatedcommunication duty-cycle ratios based at least in part on the measuredcommunication performance metrics, wherein a communication duty-cycleratio of a given mesh-network node in the one or more mesh-network nodesspecifies an amount of communication that occurs via the givenmesh-network node in the mesh network relative to an amount ofcommunication that occurs via a remainder of the one or moremesh-network nodes in the mesh network; and provide, to the one or moreoutput nodes, information addressed to the root device via the one ormore mesh-network nodes based at least in part on the communicationduty-cycle ratios, wherein the one or more mesh-network nodes comprise adynamically determined communication path in the mesh network.
 2. Theelectronic device of claim 1, wherein the candidate mesh-network nodesare selected based at least in part on estimated data rates forsuccessful communication; and wherein an estimated data rate forsuccessful communication of a given candidate mesh-network node in thecandidate mesh-network nodes is based at least in part on one of: areceived signal strength indication, airtime usage by the givencandidate mesh-network node, and an advertised throughput associatedwith the given candidate mesh-network node.
 3. The electronic device ofclaim 2, wherein at least one of the airtime usage and the advertisedthroughput are included in beacons communicated in the mesh network. 4.The electronic device of claim 1, wherein a communication performancemetric of a given candidate mesh-network node in the candidatemesh-network nodes comprises one of: a data rate for successfulcommunication, an estimated data rate for successful communication, or aratio of the data rate to an estimated maximum data rate of acommunication channel.
 5. The electronic device of claim 1, wherein thecandidate mesh-network nodes are selected based at least in part onestimated data rates for successful communication; and wherein anestimated data rate for successful communication of a given candidatemesh-network node in the candidate mesh-network nodes corresponds to athroughput between the given candidate mesh-network node and the rootdevice in the mesh network and a throughput metric corresponding to athroughput between the given candidate mesh-network node and theelectronic device.
 6. The electronic device of claim 1, wherein themeasured communication performance metrics comprise an uplinkthroughput.
 7. The electronic device of claim 1, wherein the measuredcommunication performance metrics correspond to one hop in the meshnetwork.
 8. The electronic device of claim 1, wherein the communicationperformance metrics of the candidate mesh-network nodes are measured ina round-robin fashion.
 9. The electronic device of claim 1, wherein,when a measured communication performance metric of a candidatemesh-network node exceeds the other measured throughputs by a predefinedvalue, the one or more mesh-network nodes comprise the candidatemesh-network node and the associated communication duty-cycle ratio isone hundred percent; and wherein, when maximum measured communicationperformance metrics, which are associated with at least two candidatemesh-network nodes, are within a second predefined value of each other,the one or more mesh-network nodes comprise at least the two candidatemesh-network nodes and the associated communication duty-cycle ratiosare based at least in part on ratios of the measured communicationperformance metrics of at least the two candidate mesh-network nodes.10. The electronic device of claim 1, wherein the operations ofmeasuring, identifying, determining and providing are repeated until aconvergence criterion is achieved.
 11. The electronic device of claim 1,wherein the one or more mesh-network nodes are identified and thecommunication duty-cycle ratios are determined using Bayesian analysis.12. The electronic device of claim 1, wherein the electronic device andthe two or more electronic devices comprise access points.
 13. Theelectronic device of claim 1, wherein the electronic device furthercomprises an antenna coupled to the interface circuit.
 14. Anon-transitory computer-readable storage medium for use in conjunctionwith an electronic device, the computer-readable storage medium storingprogram instructions that, when executed by the electronic device,causes the electronic device to perform operations comprising: selectingcandidate mesh-network nodes to a root device in a mesh network;measuring communication performance metrics of the candidatemesh-network nodes by providing packets addressed to the candidatemesh-network nodes, and receiving acknowledgments associated with thecandidate mesh-network nodes; identifying one or more mesh-network nodesin the candidate mesh-network nodes and determining associatedcommunication duty-cycle ratios based at least in part on the measuredcommunication performance metrics, wherein a communication duty-cycleratio of a given mesh-network node in the one or more mesh-network nodesspecifies an amount of communication that occurs via the givenmesh-network node in the mesh network relative to an amount ofcommunication that occurs via a remainder of the one or moremesh-network nodes in the mesh network; and providing informationaddressed to the root device via the one or more mesh-network nodesbased at least in part on the communication duty-cycle ratios, whereinthe one or more mesh-network nodes comprise a dynamically determinedcommunication path in the mesh network.
 15. The computer-readablestorage medium of claim 14, wherein a communication performance metricof a given candidate mesh-network node in the candidate mesh-networknodes comprises one of: a data rate for successful communication, anestimated data rate for successful communication, or a ratio of the datarate to an estimated maximum data rate of a communication channel. 16.The computer-readable storage medium of claim 14, wherein the candidatemesh-network nodes are selected based at least in part on estimated datarates for successful communication; and wherein an estimated data ratefor successful communication of a given candidate mesh-network node inthe candidate mesh-network nodes is based at least in part on one of: areceived signal strength indication, airtime usage by the givencandidate mesh-network node, and an advertised throughput associatedwith the given candidate mesh-network node.
 17. The computer-readablestorage medium of claim 14, wherein, when a measured communicationperformance metric of a candidate mesh-network node exceeds the othermeasured throughputs by a predefined value, the one or more mesh-networknodes comprise the candidate mesh-network node and the associatedcommunication duty-cycle ratio is one hundred percent; and wherein, whenmaximum measured communication performance metrics, which are associatedwith at least two candidate mesh-network nodes, are within a secondpredefined value of each other, the one or more mesh-network nodescomprise at least the two candidate mesh-network nodes and theassociated communication duty-cycle ratios are based at least in part onratios of the measured communication performance metrics of at least thetwo candidate mesh-network nodes.
 18. The computer-readable storagemedium of claim 14, wherein the operations of measuring, identifying,determining and providing are repeated until a convergence criterion isachieved.
 19. A method for establishing a mesh network, comprising: byan electronic device: selecting candidate mesh-network nodes to a rootdevice in a mesh network; measuring communication performance metrics ofthe candidate mesh-network nodes by providing packets addressed to thecandidate mesh-network nodes, and receiving acknowledgments associatedwith the candidate mesh-network nodes; identifying one or moremesh-network nodes in the candidate mesh-network nodes and determiningassociated communication duty-cycle ratios based at least in part on themeasured communication performance metrics, wherein a communicationduty-cycle ratio of a given mesh-network node in the one or moremesh-network nodes specifies an amount of communication that occurs viathe given mesh-network node in the mesh network relative to an amount ofcommunication that occurs via a remainder of the one or moremesh-network nodes in the mesh network; and providing informationaddressed to the root device via the one or more mesh-network nodesbased at least in part on the communication duty-cycle ratios, whereinthe one or more mesh-network nodes comprise a dynamically determinedcommunication path in the mesh network.
 20. The method of claim 19,wherein a communication performance metric of a given candidatemesh-network node in the candidate mesh-network nodes comprises one of:a data rate for successful communication, an estimated data rate forsuccessful communication, or a ratio of the data rate to an estimatedmaximum data rate of a communication channel.